Table 2.

Statistics of dust Heavy metals of Beijing suburban in winter/mg/kg.

Heavy Metal	Min	Max	Extreme Ratio	Mean	Median	SD	C.V
Bi	0.9	4.6	5.3	1.9	1.7	0.97	50%
Cd	1.1	3.4	3.1	1.9	1.8	0.64	34%
Co	12.7	34.4	2.7	17.7	15.1	7.27	41%
Cr	92.9	199	2.1	125.1	109.1	35.92	29%
Cu	85.9	200.5	2.3	131.9	114.8	39.68	30%
Mo	3.3	11.6	3.5	5.3	4.6	2.24	42%
Ni	34.6	80.5	2.3	48.8	44.9	11.78	24%
Pb	61.8	136.1	2.2	91.6	86.6	22	24%
V	63.6	90	1.4	80.9	81.7	7.34	9%
Zn	262.8	1000	3.8	514.5	433.7	246.05	48%
Tb	0.5	0.7	1.6	0.6	0.6	0.07	11%

C.V: variation coefficients.